The goal of this program is to design, develop, and evaluate a state-of-the-art system for ultrasonically inducing local hyperthermia in humans for use in cancer therapy. The program is composed to several interconnected subgoals which are: 1) To continue development of existing computer programs used for transducer design and beam pattern evaluation, thermal exposure calculations and resulting temperature distributions. 2) To design and evaluate ultrasound transducers that are optimised for inducing hyperthermia. 3) Install transducers with appropriate power supplies and controllers in a modified diagnostic ultrasound scanner. The central unit is a commercial OCTOSON digital ultrasound imaging system. We will add a number of additional heating transducers to the gantry in out-rigger fashion. Each transducer will be separately driven by its own power amplifier and driver. The drivers will be driven by a micro-processor based control unit. Temperatures at varius important sites within the patient will be measured with thermocouples or other devices and made available to the operator and to the control unit by means of a data acquisition system. 4) Design and install a hardware and software link between temperature monitoring devices on subjects and the microprocessor controllers within the imager for the purpose of automating the delivery of thermal dose. 5) Evaluate the system with phantoms. 6) Evaluate the system with animals. The purpose of the animal studies will be two-fold: a) determine whether focused ultrasound can be effectively delivered to deep seated abdominal masses without excessive heating of adjacent critical normal organs. b) Determine initial antitumor effects and normal tissue toxicities resulting from such treatment in pet animals with spontaneous tumors, i.e. Phase I/II Preclinical Trials. The animal portion of this project has been planned to solve the technical problems of safely and effectively heating deep seated abdominal tumors with focused ultrasound. 7) Evaluate the system with humans. a) Evaluate ability of the proposed system to achieve prescribed thermal distributions in human tumors, b) evaluate toxicity associated with the proposed ultrasound hyperthermia technique, c) compare the thermal distributions and temperature patterns achieved with the proposed device to those achieved with other hyperthermia devices, d) evaluate the imaging capability of the device, e) evaluate tumor response rates and duration of response rates and duration of response.